The present invention relates to a magnetically readable card and to a method for making the magnetically readable card as well as to an apparatus for making the magnetically readable card.
Magnetically readable cards typically comprise a polymeric sheet and a magnetic strip which is adhered to the polymeric sheet. Magnetic strips are applied to the polymeric sheet by incorporating the strips in a cover sheet and laminating the cover sheet onto a core stock sheet and then severing the laminated assembly into individual cards.
Magnetically readable cards have use as credit cards, bank cash machine cards, security passes, phone cards, hotel keys, and so on. These cards are typically constructed of a heavy, rigid vinyl polymer core with a thin vinyl polymer cover sheet or laminate bonded to opposite faces of the core. The cards may also be constructed of polystyrene and may be made of other polymeric extruded or calendered polymeric sheet substrate such as PETG, RPET, and APET. In addition to lamination to the surface of a core, cards can be used without any lamination which are called surface print cards.
The core is frequently printed. The cover sheets are transparent to allow readability of the printed material. The cover sheets are typically bonded to the core by application of both heat and pressure. To permit encoding of information on the card, the magnetically readable card includes a magnetic strip at or near the surface of the card. The magnetic strip incorporates a ferromagnetic powder such as an iron oxide and a binder including polymers such as vinyls. To provide satisfactory interaction with magnetic reading and writing equipment, the magnetic strip and the surrounding surfaces of the card should be precisely flat and free of defects. For some embodiments, however, the magnetic strip is applied with pressure sensitive to the surface of the card. The magnetic strip is raised above the surface of the card by the thickness of the strip and adhesive layer and is regarded as acceptable. Moreover, the magnetic strip should be precisely flush with the adjacent surfaces of the card and should have a uniform thickness and straight edges. The magnetic strip also must be securely bonded to the remainder of the card.
Magnetic material has typically been formed into a thin layer on a carrier layer such as a polyester sheet by a solvent coating process. The carrier sheet typically is a polyester-based polymer, such as polyethylene terephthalate, “PET.” The PET can withstand solvents used in the coating process. The formation produces a laminate which is provided with a meltable release layer disposed between the magnetic layer and the carrier layer with a heat-active adhesive directly overlying the magnetic layer. The laminate can be slit into continuous strips or tapes. The magnetic layer can be transferred from the carrier layer directly to the card by placing the strip or tape on the card so that the adhesive layer faces the card, and then applying heat and pressure through the carrier layer to melt the release layer and activate the adhesive, thereby bonding the magnetic layer to the card. The carrier layer is stripped off of the magnetic layer at this point.
In U.S. Pat. Nos. 4,149,925 and 4,231,828, magnetic material is transferred from a carrier directly to individual cards by feeding each card with a strip of the laminate superimposed thereon through a nip defined by a heated roller and a reaction roller. The carrier sheet of the laminate contacts the heated roller whereas the adhesive layer of the laminate contacts the card. Heat transferred through the carrier layer activates the adhesive layer and melts the release layer so that the magnetic material separates from its carrier layer and bonds to the card. The card as fed into the nip must include a stiff core in order to withstand heat and pressure without unacceptable distortion. With this method, handling individual cards tends to be a slow and expensive process.
Another process described in U.S. Pat. No. 5,073,221 produces a plurality of magnetically readable cards in a single production cycle. With this process, a core stock is provided as a large sheet having printed regions corresponding to a multiplicity of cards arranged in a matrix of several rows and columns across the face of the sheet with waste or “gutter” spaces between those regions corresponding to individual cards. Cover sheets or over-laminae are superimposed on the core stock and attached thereto only at an edge thereof. A plurality of strips or tapes of the aforementioned laminae are unwound from individual reels and laid onto one cover sheet so that each strip or tape lies in registration with the individual printed card regions. The magnetic material in each strip or tape is “tacked” or bonded to the cover sheet by localized application of heat and pressure at only those locations corresponding to the waste or gutter spaces between the printed card regions on the sheet of the core stock. The carrier layer of each strip or tape is removed, leaving the magnetic material closely attached to the cover sheet.
In another embodiment, polymeric sheets are fed into a machine whereby one or multiple rolls of the magnetic strip material with heat activated adhesive on the back of the strip are aligned and applied to the sheet using a heat transfer method. A heated roller applies pressure to the magnetic strip material against the polymeric material whereby activating the heat activated adhesive and adhering it to the polymeric material.
In one other embodiment, polymeric sheets are fed into a machine whereby one or multiple rolls of the magnetic strips with pressure sensitive adhesive on the back of each strip is aligned and applied to the sheet. The pressure sensitive adhesive liner is removed from the magnetic strip to expose adhesive as a roller applies pressure to the magnetic strip material against the polymeric material, thereby adhering it to the polymeric material.
The entire composite is then placed between a pair of heated platens and subjected to heat and pressure so as to bond the cover sheets to the core stock and fuse the magnetic material with the adjacent cover sheet. Following the lamination step, individual cards are severed from the sheet of the core stock by die cutting. A preliminary tacking step may cause some distortion of the over-laminae or underlying core stock and therefore some unevenness in the resulting magnetic layer. The distortion and unevenness is confined to the waste or “gutter” areas of the sheets. The distorted regions, therefore, do not appear in the finished cards after the die-cutting operation.
This fabrication technique requires complex equipment and procedures. The tacking equipment must be discontinuous to limit distortion of the over-laminae to the waste areas of the sheet. The discontinuous process of unwinding only a limited length of each strip or tape and laying some onto a subassembly of cover layers and sheet of core stock of limited length is slow and troublesome. The original sheet of core stock must necessarily include waste areas to provide locations for tacking. Therefore, this process results in waste of materials. The composite, after the preliminary tacking step, is relatively fragile and poses considerable handling difficulties.